Graeme, I am confused (nothing unusual in that). The second photograph shows S.66. I have that photograph as a C1. Having said that, I have also seen a photograph of the C1W, float plane version, that has the same tail/fin structure as your C1 version. It also has the two booms painted in a darker colour, as does your photograph. My problem is that there seems to be very little written about the Ago C1 and C2.
Richard.